A Genma is a person who is originally from japan and only talks when necessary also known as the mute ninja (silent-assassin). He is passionate to follow the way of the samurai, however he can be a threat to you and your family so make sure you don’t cross him because it will turn him into the 悪魔 devil which will lead to your demise.

•fighting spirit; wildness.
noun: devil
"he was dangerous when the devil was in him"•a thing that is very difficult or awkward to do or deal with.
"it's going to be the very devil to disentangle"2. informal
a person with specified characteristics.
"the cunning old devil"
synonyms: wretch, unfortunate, creature, soul, person, fellow; Moreinformalthing, beggar, bastard; vulgar slangsod, bugger "the poor devils looked as though they could do with some refreshment"